United are reportedly looking to strengthen their backline in the winter transfer market after losing defenders Rafael, Phil Jones, Jonny Evans, Luke Shaw and Marcos Rojo to injuries.
Godin has been strongly linked with a move to Old Trafford, with United manager Louis van Gaal reportedly keen to acquire the Uruguay international's services.
But when asked whether Atletico would accept an offer in the region of 20million euros from United for Godin, Simeone told the Spanish media: "Let's talk about something else.
"How much? Twenty? For Godin?
"It must be a mistake."
Godin, who helped Uruguay reach the last-16 of the World Cup in Brazil, is under contract with the Spanish champions until June 2018.
The 28-year-old centre-back has been a key player in Simeone's squad since moving to the Vicente Calderon stadium in 2010 from Villarreal.
Godin started in 34 league games last season and scored four goals, including the crucial equaliser against Barcelona in the final game of the 2013-14 campaign to hand Atletico their first league title since 1996
Source: PA